/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.iotdb.db.mpp.plan.planner.plan.node.process;

import org.apache.iotdb.db.mpp.plan.planner.plan.node.PlanNode;
import org.apache.iotdb.db.mpp.plan.planner.plan.node.PlanNodeId;
import org.apache.iotdb.db.mpp.plan.planner.plan.node.PlanNodeType;
import org.apache.iotdb.db.mpp.plan.planner.plan.node.PlanVisitor;
import org.apache.iotdb.tsfile.utils.ReadWriteIOUtils;

import java.io.DataOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.List;
import java.util.Objects;

/**
 * LimitNode is used to select top n result. It uses the default order of upstream nodes
 */
public class LimitNode extends SingleChildProcessNode {

    private final int limit;

    public LimitNode(PlanNodeId id, int limit) {
        super(id);
        this.limit = limit;
    }

    public LimitNode(PlanNodeId id, PlanNode child, int limit) {
        super(id, child);
        this.limit = limit;
    }

    public int getLimit() {
        return limit;
    }

    @Override
    public PlanNode clone() {
        return new LimitNode(getPlanNodeId(), this.limit);
    }

    @Override
    public List<String> getOutputColumnNames() {
        return child.getOutputColumnNames();
    }

    @Override
    public <R, C> R accept(PlanVisitor<R, C> visitor, C context) {
        return visitor.visitLimit(this, context);
    }

    @Override
    protected void serializeAttributes(ByteBuffer byteBuffer) {
        PlanNodeType.LIMIT.serialize(byteBuffer);
        ReadWriteIOUtils.write(limit, byteBuffer);
    }

    @Override
    protected void serializeAttributes(DataOutputStream stream) throws IOException {
        PlanNodeType.LIMIT.serialize(stream);
        ReadWriteIOUtils.write(limit, stream);
    }

    public static LimitNode deserialize(ByteBuffer byteBuffer) {
        int limit = ReadWriteIOUtils.readInt(byteBuffer);
        PlanNodeId planNodeId = PlanNodeId.deserialize(byteBuffer);
        return new LimitNode(planNodeId, limit);
    }

    @Override
    public String toString() {
        return "LimitNode-" + this.getPlanNodeId();
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) {
            return true;
        }
        if (o == null || getClass() != o.getClass()) {
            return false;
        }
        if (!super.equals(o)) {
            return false;
        }
        LimitNode that = (LimitNode) o;
        return limit == that.limit;
    }

    @Override
    public int hashCode() {
        return Objects.hash(super.hashCode(), limit);
    }
}
